I was watching a video about how to knit socks, and the woman in the video used a similar yarn winder as the one from KnitPicks. She blasted through half a big skein of yarn in about a minute, so I would think that this would make your life much easier--even with lots and lots of yarn.
If you get one, please do give us an update. I've been wanting to know how these work for others ever since I saw that video.
Meanwhile, must teach hubby a new trick!